Configuring the Physical Subscriber Line for RADIUS Access and Accounting

Configuring a physical subscriber line for RADIUS Access and Accounting enables an L2TP access concentrator (LAC) and an L2TP network server (LNS) to forward RADIUS NAS-Port and NAS-Port-Type attribute values for PPP over ATM, PPPoE over ATM, and PPPoE over IEEE 802.1Q VLANs.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see
Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to
www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Prerequisites for Configuring the Physical Subscriber Line for RADIUS Access and Accounting

You must perform the configuration procedures in the "Configuring RADIUS" chapter in the Cisco IOS Security Configuration Guide.

You must perform the PPP over ATM configuration procedures in the "Providing Protocol Support for Broadband Access Aggregation of PPP over ATM Sessions" module.

You must perform the PPPoE configuration procedures in the "Providing Protocol Support for Broadband Access Aggregation of PPPoE Sessions" module.

Note

The PPP extended NAS-Port format increases the size of the NAS-Port attribute field to 32 bits and changes the NAS-Port attribute format to provide the RADIUS server with details about the ATM port, the virtual path identifier (VPI), the virtual channel identifier (VCI), and, for IEEE 802.1Q VLANs, the VLAN ID.

Information About Configuring the Physical Subscriber Line for RADIUS Access and Accounting

PPP over ATM and PPPoE over ATM NAS-Port Attribute Field Format

For PPP over ATM and PPP over ATM, the PPP extended format enables the
NAS-Port attribute field to provide details about the ATM interface, VPI, and
VCI. The figure below shows the format of the NAS-Port attribute field when the
PPP extended NAS-Port format is configured and PPPoA over ATM or PPPoE over ATM
is being used.

Figure 1. Format of the NAS-Port Attribute Field for PPP over ATM and PPPoE
over ATM

The interfaces, VPI, and VCI correspond to the interface and virtual
circuit (VC) on which the ppp session entered the router.

Note

For Cisco 6400 series routers, the interface, VPI, and VCI
correspond to the interface and VC on which the session entered the Cisco 6400
node switch processor (NSP).

The figure below shows the format of the 8-bit interface field. For
platforms that do not have slots or modules, the slot and module fields is 0.

Figure 2. Format of the Interface Field for PPP over ATM and PPPoE over ATM

The NAS-Port-Type value for PPP over ATM and PPPoE over ATM is 5, which
is the value for virtual port types.

PPPoE over IEEE 802.1Q VLANs Format

For PPPoE over 802.1Q VLANs, the PPP extended format provides details
about the interface and the VLAN ID. The figure below shows the format of the
NAS-Port attribute field when the PPP extended NAS-Port format is configured
and PPPoE over an IEEE 802.1Q VLAN is being used.

Figure 3. Format of the NAS-Port Attribute Field for PPPoE over 802.1Q VLANs

The figure below shows the format of the 8-bit interface field. For
platforms that do not have slots or modules, the slot and module fields will be
0.

Figure 4. Format of the Interface Field for PPPoE over 802.1Q VLANs

The NAS-Port-Type value for PPPoE over 802.1Q VLANs is 15.

How to Configure the Physical Subscriber Line for RADIUS Access and Accounting

Configuring the LAC for RADIUS Port Identification for PPP

Perform this task to configure the LAC for RADIUS port identification for PPP.

SUMMARY STEPS

1.enable

2.configureterminal

3.radius-serverattributenas-portformatd

4.end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2

configureterminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3

radius-serverattributenas-portformatd

Example:

Router(config)# radius-server attribute nas-port format d

Specifies that PPP extended NAS-Port format that is used for RADIUS accounting.

Step 4

end

Example:

Router(config-bba-group)# end

Ends the configuration session and returns to privileged EXEC mode.

Configuring the LNS for RADIUS Port Identification for PPP

Perform this task to configure the LNS for RADIUS port identification for PPP.

Note

In order for the LNS to forward PPP extended NAS-Port format values to the RADIUS server, both the LAC and the LNS must be Cisco routers running a Cisco IOS image that supports RADIUS port identification for PPP.

SUMMARY STEPS

1.enable

2.configureterminal

3.radius-serverattributenas-portformatd

4.vpdnaaaattributenas-portvpdn-nas

5.end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2

configureterminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3

radius-serverattributenas-portformatd

Example:

Router(config)# radius-server attribute nas-port format d

Specifies that PPP extended NAS-Port format that is used for RADIUS accounting.

Step 4

vpdnaaaattributenas-portvpdn-nas

Example:

Router(config)# vpdn aaa attribute nas-port vpdn-nas

Enables the LNS to send PPP extended NAS-Port format values to the RADIUS server for accounting.

LNS Configuration for RADIUS Port Identification for PPP Example

In the following example, the LNS is configured to recognize and forward PPP extended NAS-Port format values to the RADIUS server. The PPP extended NAS-Port format must also be configured on the LAC for this configuration to be effective.

RFCs

Technical Assistance

Description

Link

The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.

To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

Feature Information for Identifying the Physical Subscriber Line for RADIUS Access and Accounting

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to
www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Table 1 Feature Information for Identifying the Physical Subscriber Line for RADIUS Access and Accounting